Most occasional invaders enter structures because outside weather conditions become too hostile for their survival. However, occasional invaders are often just nuisance pests because they cannot survive for long periods of time indoors.
Although occasional invaders may enter structures in large numbers, they are often nothing more than an annoying nuisance. However, there are a few specific pests that can cause non health-related problems. Stink bugs are harmful to the agricultural industry because they destroy crops. Boxelder Bugs and ladybugs may exude a defensive fluid when crushed that could stain curtains, drapes, clothing and other fabrics. Silverfish infest paper, particularly wallpaper, books and envelopes, so these materials could become damaged over time.